This happened to me with a can of tresemme,but when I was trying to spray it,it suddenly started working again but wouldn't stop!Got spray in my eyes,moth,nose,mirror etc.Kept pressing it a few times and it eventually stopped.I e-mailed them and told them what had happened and as well as an apology they sent me a five pound voucher!
I would follow the advice of welshibranr and also scrub the nozzle with a toothbrush to help remove the spray.